Self-cloning of the Catalase Gene in Environmental Isolates Improves Their Colony-forming Abilities on Agar Media.

Hydrogen peroxide (H ₂ O ₂ ) inhibits microbial growth at a specific concentration. However, we previously isolated two environmental bacterial strains that exhibited sensitivity to a lower H ₂ O ₂ concentration in agar plates. Putative catalase genes, which degrade H ₂ O ₂ , were detected in their genomes. We herein elucidated the characteristics of these putative genes and their products using a self-cloning technique. The products of the cloned genes were identified as functional catalases. The up-regulation of their expression increased the colony-forming ability of host cells under H ₂ O ₂ pressure. The present results demonstrated high sensitivity to H ₂ O ₂ even in microbes possessing functional catalase genes.